Using OPENCV to read the image as an OpenGL texture image of the implementation of the method __filter

The first step in implementing the texture mapping of three-dimensional objects in OpenGL is to read the picture and then specify the picture as a texture picture. The first project I took over was to read the texture picture by a special function to read the BMP picture. This function has three disadvantages:

1, can only read BMP pictures, can not read jpg,ppm and other types of pictures, to use other types of pictures, they must be converted into BMP pictures;

2, can only read 2 power and 2 power to the size of the picture, otherwise the function can not correctly read the picture content;

3, can only read 24-bit BMP pictures.

The above three shortcomings make our procedure have the very big limitation. To that end, after learning the OPENCV, I used the cvloadimage () function in OpenCV to solve the problem.

Our solution is as follows:

First, use the following line of code to read the picture into memory:

iplimage * iface = Cvloadimage (szfilename);

Then use the following code to open a memory space in memory that is the same size as the read image:

m_new_face_bmpbytes = (unsigned char *) malloc (sizeof (unsigned char) *iface->imagesize);

if we read 24-bit RGB color pictures, then iface->imagesize several pictures of the pixel size times 3, such as our picture is 512*512 size so iface->imagesize is 512*512*3.

We then use the following code to copy the actual data portion of the picture in Iface to the memory space we have set:

memcpy (m_new_face_bmpbytes,iface->imagedata,sizeof (unsigned char) *iface->imagesize);

Iface->imagedata is the first address of the space for storing picture pixel data

Then we save the size of the picture:

M_new_face_width = iface->width;
M_new_face_height = iface->height;

Finally, we set the image data pointed to m_new_face_bmpbytes as the texture image in OpenGL:

Glgentextures (1, &m_texname); 1 represents the number of textures to be generated, M_texname is used to store the indexes that generate textures, which are used when binding textures

Gltexenvi (gl_texture_env, Gl_texture_env_mode, gl_modulate);
Gldisable (gl_lighting);
Glenable (gl_texture_2d);

Glbindtexture (gl_texture_2d, m_texname);
Gltexparameteri (gl_texture_2d, Gl_texture_min_filter, gl_linear);
Gltexparameteri (gl_texture_2d, Gl_texture_mag_filter, gl_linear);
Gltexparameteri (gl_texture_2d, gl_texture_wrap_s, gl_repeat);
Gltexparameteri (gl_texture_2d, gl_texture_wrap_t, gl_repeat);
Glteximage2d (gl_texture_2d, 0, Gl_rgb8, m_new_face_width, m_new_face_height, 0,
Gl_bgr_ext, Gl_unsigned_byte, m_new_face_bmpbytes);

This completes the setting of the texture image that we have read into as OpenGL.